This invention relates to an improved wood beam fabricated from a pair of wood chord members and plywood web members interconnecting said chord members by means of glued tongue and groove joints.
The rising cost of sawn lumber in general, and the scarcity of high quality wood capable of producing beams of large size, make it necessary to develop improved processes for fabricating large beams from less expensive and more available wood products. Fabrication also permits more efficient design requiring less wood to make a beam of a given strength. This not only saves wood but also reduces the cost of transportation and facilitates the erection of wooden structures.
Previous attempts to form fabricated wood beams usually require a considerable amount of metal hardware, which hardware involves an additional item of cost as well as time and labor in assembly to attach and secure a multiplicity of fastening devices. On the other hand, known methods of fabricating wood beams by gluing various members together have resulted in a time consuming operation involving external clamps to hold the members together in assembled relation while the glue is setting. Then, if heating means are used to set the glue more quickly, the cost is increased by the amount of heating energy employed.
Objects of the present invention are, therefore, to provide an improved fabricated wood beam, to provide a beam requiring less wood than sawn lumber for supporting a given load, to provide a beam having an improved structural shape and to provide a beam having plywood web members interconnecting a pair of chord members by means of glued tongue and groove joints of a self-locking dovetail type which hold the members together in assembled relation without external clamps while the glue is setting.